This invention generally relates to a circuit board inspecting apparatus, and specifically relates to an apparatus for automatically inspecting solder portions of a printed circuit board.
Japanese published unexamined patent application 1-219548 discloses an apparatus for automatically inspecting solder portions of a printed circuit board by using the fact that a good solder portion and a defective solder portion exhibit different accumulative frequency distributions of luminance. The apparatus of Japanese application 1-219548 has a two-dimensional camera to generate data representing luminances of the solder portions of the printed circuit board. An accumulative frequency distribution of luminance is derived from the luminance data. The solder portions of the printed circuit board are checked by analyzing the accumulative frequency distribution of luminance.